On-line service provision method, and equipment for implementing such a method

ABSTRACT

The invention relates to the provision of services. According to the invention, a service session supervision platform ( 10 ) is disposed between an access network ( 1 ) and an input node ( 12 ) of a service-hosting network. During the provision of a service, at least one atomic section is first defined, said section consisting of a determined sequence of events which are involved in message exchanges with a subscriber. The supervision platform detects and flags events forming the beginning or end of an atomic section in a service session in progress for a subscriber by means of the access network. A communication interrupt request from a subscriber is processed by ascertaining if an atomic section is in progress for said subscriber according to the atomic section beginnings and ends flagged by the supervision platform, in order to determine whether or not the communication must be interrupted immediately.

The present invention relates to on-line service mediation techniques.

In particular, it relates to content services that can be supplied viathird generation (3G) cellular radio communication networks of the UMTStype (Universal Mobile Telecommunications System). It is more generallyof interest to Internet service providers (ISP), whether the subscriberaccess is by radio, by wire or by other means. The term “3G services” isused below to denote the services affected by the invention, withoutthis being in any way limiting.

The rating of these services is difficult to perfect. The serviceproviders put in place an information system (IS) to deal with customercare and billing (CC&B). These ISs provide them with the ability to ratethe 3G services with a large number of metrics available todifferentiate these services in terms of rating and billing.

For this, the manufacturers offer platforms to provide SCP-type contentmediation (SCP being an intelligent network term standing for “servicecontrol point”). These manufacturers include NARUS, ENITION, VoluBill,P-Cube, etc.

All these platforms provide a functionality for analyzing andsupervising IP (Internet Protocol) packets exchanged within the contextof 3G service sessions initiated by the user of a 3G terminal or of aworkstation connected to the Internet. They have the ability to analyzethe information encapsulated in the IP packets up to layer 7(Application) of the OSI protocol architecture model. This enables themto apply rating metrics taking into account IP addresses, TCP(Transmission Control Protocol) ports, URL (Uniform Resource Locator)resources, etc.

These platforms are normally incorporated in the same place in the ISdomain of the CC&B: between the endpoint node of the access network (3Gcellular or fixed line), and the first node of the IP network hosting 3Gservices (ISP network or Internet network). This first input node in the3G services IP network is most often a 3G services “portal”.

Some of these platforms, for example the “NetToll” platform marketed byENITION, have a functionality enabling the 3G service provider to beautonomous in the phase of creating his 3G services. A protocol (called“NetPolicy” in the case of the “NetToll” platform) enables the 3Gservice provider to define and create all the data that makes up theinformation model of his new 3G service. The 3G service provider thushimself creates all the data relating to the new service in the databaseforming the service reference base of the “SCP-Like Content Mediation”platform.

For the rating of 3G services, the most difficult problems to resolve inthis IS domain of the CC&B stem:

-   -   from the current impossibility of guaranteeing a quality of        service (QoS) that is completely deterministic for the        “delivery” of the 3G services;    -   from the “multi-session” nature of the technologies supporting        these services (UMTS and its upgrades, or IP fixed networks).        This means that, for example, the end user of a 3G terminal        (mobile phone, personal digital assistant, etc.) can set up a        plurality of 3G service sessions running in parallel.

Any mechanism that helps to improve the QoS perceived by the user whosets up 3G service sessions is desirable to facilitate the hitherto slowtake-off of the 3G services.

A particular problem is that of the perception by the end user ofcertain communication interruptions which can be due to various reasons.In the absence of particular precautions, there is a risk of such aninterruption being perceived very abruptly by the customer, which maydiscourage the customer from subscribing to this type of service. Thesuccess of a new 3G service runs the risk of being compromised if itbrings into play circumstances in which such an abrupt interruption isparticularly disagreeable to the customer (for example, if he does notknow whether his bank account has been debited).

The 3G service session interruption decision situations include inparticular the following:

-   -   detection by the rating system that a zero threshold is reached        on the account associated with the rating of a service (for        example, the account associated with the rating of the service        transport part);    -   certain legal obligations, such as the protection of underage        persons with respect to “addictive” behaviors that urge them        toward excessive consumption;    -   for companies, the needs to protect and monitor the consumption        of “enterprise” type 3G services by their field or office        employees etc.

An object of the present invention is to propose a mechanism forimproving the ergonomics of the on-line services, in particular in casesof involuntary communication interruption.

The invention thus proposes an on-line service provision method, whereinin particular a service session supervision platform is placed betweenan access network and an input node of a service-hosting network. Thismethod comprises the following steps in relation to at least oneservice:

-   -   a priori defining, in the running of said service, at least one        atomic section consisting of a determined sequence of events        which are involved in message exchanges with a subscriber, and        identifying a first event at the start of the atomic section and        at least one second event at the end of the atomic section; and    -   configuring the supervision platform so that it detects the        events identified in a session of said service in progress for a        subscriber via the access network and flags a start of atomic        section for said subscriber in response to the detection of the        first event and an end of atomic section for said subscriber in        response to the detection of a second event.

According to the invention, a communication interrupt request from asubscriber is processed by ascertaining whether an atomic section is inprogress for said subscriber according to the atomic section beginningsand ends flagged by the supervision platform, in order to determinewhether the communication must at least partly be interruptedimmediately, that is to say whether some or all of the current sessionsmust be interrupted immediately.

If a service is interrupted in the middle of a sequence forming asemantically uniform and meaningful whole, this service is perceived ascorrupted and aborted in an indeterminate state by its customer. Morespecifically, a more in-depth analysis shows that numerous examples of3G services thus contain sequences that cannot be interrupted withoutdamage from the point of view of the QoS perceived by their consumer.

Such a sequence is here called an “atomic section” in reference to theterminology used in transaction-oriented information processingtechniques, in which the atomicity of a transaction means that it mustbe considered as an indivisible operation, which can only be run in itsentirety, or, failing this, be cancelled in its entirety.

The atomic sections do not necessarily relate to all of the servicesthat can be accessed via the hosting network, but only those of theseservices for which there are sequences where the concept of atomicityapplies.

As an example, services that use bids are run according to a genericschema normally comprising the following steps:

-   -   A/ the bidding application server proposes its bids;    -   B/ the customer notifies his desire to make a bid and sends a        message to “deposit” his bid;    -   C/ the bidding application server notifies the customer that the        bid has been “deposited” as it was received, and requests        confirmation of this bid by the customer;    -   D/ the customer sends his confirmation;    -   E/ the server notifies “closure” of the bid deposited and        confirmed by the customer;    -   F/ subsequently, the server notifies the customer of the result        of his bid.

In this sequence of steps, it can be seen that, from step B/ to step E/,any interruption of the session supporting this bidding service will beperceived abruptly by the customer. Often, this customer does not knowthe exact status of the bid as it will be processed by the applicationserver. Such uncertainty is by its very nature likely to make him rejectthe service.

For this bidding service, the sequence of events from step B/ to step E/can therefore be qualified as an atomic section. A supervision platform,for example of the “SCP-like content mediation” type, can be arrangedand configured according to the invention to detect such events, forexample by examining as far as the application layer the IP packetsexchanged with the customer during the session, and flagging them sothat the interrupt requests that are likely to occur are processedwisely.

This processing of the interrupt requests involving the atomic sectionscan be performed in the IS of the CC&B at different levels: accessnetwork operator, ISP, content provider, content aggregator, site host,etc., according to whether these players are responsible for the ratingof a certain part of the service as delivered.

As early as the design phase of a 3G service, the designer is normallyable to identify all the atomic sections of this service. Furthermore,he is in a position to determine which event or action constitutes thepoint of entry into an atomic section, and which event or actioncharacterizes the point of exit from the atomic section, and thereforeto define the parameters used in the method. The method thus providesthe 3G service developer with a toolbox with which he can, depending onthe semantics of his service, parameter the supervision platform toavoid unwanted service interruptions.

It is considered that most of the on-line market-standard 3G servicescontain this concept of atomic section and therefore potentially benefitfrom the invention. Such is also the case for other services, inparticular multimedia.

The communication relevant to the decision, taken by considering theexistence or not of an atomic section for the subscriber, can relate toall of the current sessions for this subscriber or to just some of thesesessions. If the request concerns the interruption of one session only,the examination of the atomic section condition can be limited to thesession concerned.

Often, the request relates to all the sessions, for example, because itoriginates from the service transport rating. If there is an atomicsection in progress in a service session, this session can be maintained(temporarily) while any other sessions in progress (with no atomicsection at the time in question) can be interrupted immediately. Thehandler could also decide to maintain these other current sessions,particularly if they relate to related services.

The context handler can, in particular, observe a hierarchical structureof the services taken into account by the service rating devices. Forexample, in certain systems, the concept of “service cone” correspondingto a set of services likely to be involved in the context of a sessionof a given service (cone summit) is known. For example, the transportservice can be seen as the apex of a cone made up of the transportedservices. One of these transported services can itself be the apex of acone, which means that, while it is running, it can offer to access orreturn to other dependent services (belonging to this cone). In anembodiment of the invention, the processing of an interrupt request fora service S thus includes an analysis by the context handler of anyatomic sections that might exist for sessions of any service belongingto the smallest of the nested cones including this service S, and thetemporary maintenance of the current sessions for the services of thissmallest cone if there is such an atomic section. The data specifyingthis cone can be at least partly accessible to the context handler sothat it can perform this analysis. This analysis of the servicehierarchy can also be undertaken by the entity originating from theinterrupt request, which accordingly selects the sessions or theservices for which the interruption is required.

Another aspect of the present invention relates to an on-line servicecontrol system, comprising a service session supervision platform placedbetween an access network and an input node of a service-hostingnetwork, and a context handler to communicate with different functionalunits including the supervision platform in order to store informationon service sessions in progress for subscribers via the access network.At least one atomic section consisting of a determined sequence ofevents which are involved in message exchanges with a subscriber is apriori defined in the running of at least one service by identifying afirst event at the start of the atomic section and at least one secondevent at the end of the atomic section. The supervision platformincludes means for detecting the events identified in a session of saidservice in progress for a subscriber via the access network and forflagging to the context handler a start of atomic section for saidsubscriber in response to the detection of the first event and an end ofatomic section for said subscriber in response to the detection of asecond event. The context handler includes means of keeping an atomicsection indicator stored for each subscriber up-to-date on the basis ofatomic section beginnings and ends flagged by the supervision platformand of processing a communication interrupt request from a subscriberaccording to the atomic section indicator stored for said subscriber inorder to determine whether the communication must at least partly beinterrupted immediately.

Another aspect of the present invention relates to a service sessionsupervision platform for an on-line service control system, comprising:

-   -   means of connection on the one hand to an access network and on        the other hand to an input node of a service-hosting network;    -   means of receiving specification elements of at least one atomic        section in at least one on-line service, consisting of a        determined sequence of events which are involved in message        exchanges with a subscriber in the running of at least one        service, said specification elements describing a first event at        the start of the atomic section and at least one second event at        the end of the atomic section;    -   means of analyzing traffic passing between the access network        and the input node of the service-hosting network to detect said        first and second events in a session of said service in progress        for a subscriber via the access network; and    -   means of communication with a context handler storing        information on service sessions in progress for subscribers via        the access network, including at least one atomic section        indicator, to flag to the context handler a start of atomic        section for said subscriber in response to the detection of the        first event and an end of atomic section for said subscriber in        response to the detection of a second event.

Another aspect of the present invention relates to a context handler foran on-line service control system, comprising:

-   -   means of communication with different functional units including        a service session supervision platform placed between an access        network and an input node of a service-hosting network;    -   means of storing information on service sessions in progress for        subscribers via the access network, said information including,        for at least one service session in progress for a subscriber,        an atomic section indicator kept up-to-date on the basis of        atomic section beginnings and ends flagged by the supervision        platform; and    -   means of processing a communication interrupt request from a        subscriber according to the atomic section indicator stored for        said subscriber in order to determine whether the communication        must at least partly be interrupted immediately.

The developer can also, using this agent, define a maximum durationconsidered to be normal for a given atomic section.

Another aspect of the present invention relates to a software agent foran on-line service developer, comprising instructions for performing thefollowing operations on running the software agent in a computer machinecommunicating with a service session supervision platform placed betweenan access network and an input node of a service-hosting network:

-   -   determination, in the running of a service, of at least one        atomic section consisting of a determined sequence of events        which are involved in message exchanges with a subscriber;    -   identification of a first event at the start of the atomic        section and at least one second event at the end of the atomic        section; and    -   configuration of the supervision platform so that it detects the        events identified in a session of said service in progress for a        subscriber via the access network and flags a start of atomic        section for said subscriber in response to the detection of the        first event and an end of atomic section for said subscriber in        response to the detection of a second event.

Other features and advantages of the present invention will becomeapparent from the description below of non-limiting exemplaryembodiments, with reference to the appended drawings, in which:

FIG. 1 is a diagram of a system according to the invention and itsenvironment;

FIG. 2 is a diagram illustrating operations implemented in an exemplarysystem according to the invention for keeping an atomic sectionindicator up-to-date; and

FIG. 3 is a flow diagram of a communication interrupt request processingprocedure that can be used in a system according to the invention.

In the application of the invention described below, the servicesconcerned are 3G services delivered to subscribers via a UMTS typeaccess network 1. It will be understood that the access technologyavailable to the subscribers can in fact be of any kind (local or widearea network, wired or wireless network, etc.).

A UMTS type third generation cellular radio network comprises on the onehand a core network 2 and on the other hand a radio access network 3.The core network 2 presents similarities with the GPRS (GeneralizedPacket Radio Service) technology, and thus includes a set of meshedswitches called GSN (GPRS Support Node) including serving nodes 4, orSGSN (Serving GSN), linked to the radio access network 3 and gatewaynodes 5, or GGSN (Gateway GSN), linked to external networks such ason-line service provision networks or the Internet. Some of the switchesof the core network are linked to a subscriber database 6 (Home LocationRegister, HLR) used to manage the mobile subscribers of the cellularnetwork. The radio access network 3, of UTRAN (UMTS Terrestrial RadioAccess Network) type, for example, is made up of radio base stations 7distributed over the coverage area of the network to offer radio linkswith the 3G terminals 8 and base station control units 9 linked to SGSNs4.

At the interface between a GGSN 5 and an external network, there isoften a service session supervision platform 10 of the “SCP-like contentmediation” type. In the example represented in FIG. 1, this platform 10is placed between the GGSN 5 and an Internet portal 12 giving access toservices provided by various content providers (CP) 13.

The 3G terminals are designed to operate according to the IP protocol.The first router seen by the terminals of the subscribers of theoperator managing the portal is the GGSN 5. The supervised IP trafficexchanged by these terminals 8 thus passes through the supervisionplatform 10 which is able to detect all sorts of events in this traffic.The events taken into account are programmable and the platform 10offers the service developer programming tools with which to configurethese events and the behaviors to be adopted when they are detected.

Conventionally, the switches of the core network 2 are linked tocellular service rating devices, either directly, or via a charginggateway (CG) 14, or via a service control point (SCP) 15 of anintelligent network architecture. These rating devices include, forexample, a unit 16 for collecting call detail records (CDR) from thecore network 2 and/or IP detail records (IPDR) resulting from the IPtraffic analysis performed by the supervision platform 10, a ratingsystem 17 which generates accounting data from the CDRs and IPDRscollected, and a billing system 18 for producing the customer bills fromthe rating elements supplied by the system 17.

The “SCP-like content mediation” type supervision platform 10 isprovided with capabilities to implement all or most of the metricsrepresentative of the rating of the 3G services. It generates CDRs,IPDRs or any other format of record intended for the rating system 17.

In some cases, rating devices can provoke an interruption of theinformation transport service for a given mobile subscriber. This may,for example, occur when the rating system 17 detects that a zerothreshold has been reached in the account associated with the rating ofthe transport of the 3G service sessions for the subscriber. Suchinterruptions can also occur at the request of other CC&B components.

Other interrupt request cases can be induced by rating devices takingaccount of the 3G services. In particular, interrupt requests can takeinto consideration a service cone concept as described previously,either in how to generate these requests in the rating devices, or inhow they should be processed.

The IS domain of the CC&B has the capability to deal with such sessioninterruption cases non-abruptly, based on a real-time knowledge of thestate of the sessions initiated by the user of the 3G terminal. Morespecifically, the invention provides for a functionally centralizedmechanism for managing the context of all the service sessions initiatedby each 3G subscriber. An IS component of the CC&B domain (in the broadsense) must therefore host and manage centrally the 3G service sessioncontexts. This IS functional component 20 is here called a “contexthandler”.

According to the invention, the context handler 20 is kept informed inreal time of the starts and ends of atomic sections by the supervisionplatform 10, and it keeps, for each current 3G session for a subscriber,a Boolean variable up-to-date, the value of which indicates whether thatsession is in an atomic section.

An IS component issuing a session interrupt request (for example, therating system 17) then transmits its request to the context handler 20which looks at the overall situation of the activities of thesubscriber. If one of his active sessions is in an atomic section, thenthe context handler 20 will be able to wait for the end of this atomicsection before passing on the interrupt command, in accordance with aneconomic logic of the service concerned. A guard timer can be providedto protect the operator against an abnormally lengthy use of an atomicsection.

The above mechanism therefore provides the operator with technical meansenabling him to control and differentiate the processing of 3G servicesession interruption cases.

The context handler 20 can be incorporated in an existing IS componentof the operator, such as the supervision platform 10 or the portal 12.It can also form a separate element as shown diagrammatically in FIG. 1.

The method requires an appropriate design and programming of thesupervision platform 10 for it to detect events interpreted as startsand ends of atomic sections for each session of each subscriber.

The atomic sections are first identified by the designer of a 3Gservice, as are the events that mark their start and end. Hisapplication server can have an “agent” enabling him to communicate withthe “SCP-like content mediation” type platform 10 to specify differentevents to be detected in the IP traffic related to the service(start/end of service session, start/end of each atomic section in sucha session, etc.) and the actions required, including notifications to beaddressed to the context handler 20 for it to keep the context of thesessions in progress up-to-date for the subscriber. The service providercan thus define, with an appropriate and secured application protocol,the data of the information model of his service.

A number of procedures can be used by the software agent made availableto the service designer or developer. One possibility consists insubmitting forms of predefined format, for example in the form of HTML(HyperText Markup Language) pages, that the agent completes andtransmits to the platform 10 on the basis of data entered by the user.Another possibility consists in providing an exchange of successivemessages between the agent and an additional software module of theplatform 10 during which the agent sets up a communication session withthe platform, enabling the user to indicate first his desire to specifyan atomic section for a given server and then to be questioned to definethe atomic section start or end event and optional parameters (forexample, the timer T₀ parameter discussed later).

In the particular example of a bidding service, as explained above, thesupervision platform 10 will be programmed to detect the messagescorresponding to steps B/ (the customer 8 sends a message to deposit abid) and E/ (the server 13 notifies closure of the bid deposited andconfirmed) according to the format of these messages adopted in theimplementation of the service.

While the service is running, the supervision platform 10 and thecontext handler 20 cooperate for example in the way illustrated in FIG.2.

The setting up of a service session for a subscriber is first detectedby the platform 10 (step 30), which notifies the context handler 20 ofthis with a session number (j), so that the latter creates a record forthis session (step 31), by initializing the atomic section Booleanindicator SA(j) to the value FALSE. If the subscriber previously had nosession in progress, the step 31 includes the creation of a context forthe subscriber with the first record. If the subscriber enters into apredefined atomic section (in our example, he deposits a bid), thecorresponding message is detected by the platform 10 (step 32), which inreal time notifies the context handler 20 of the start of atomic sectionin session number j. The context handler 20 then updates the atomicsection indicator SA(j) in step 33, assigning it the value TRUE, and itnotes down the time at which it was notified of the start of the atomicsection. The supervision platform 10 also flags the exit from the atomicsection, detected in step 34, to the context handler 20, so that thecontext handler can update the atomic section indicator SA(j) in step 35by assigning it the value FALSE. Following the closure of the session,detected in step 36 by the platform 10, the context handler 20 deletesthe record relating to the session j (and the context of the subscriberif the latter no longer has any 3G service session in progress).

A process of the type illustrated by FIG. 2 is conducted for each typeof atomic section defined for each 3G service supporting thefunctionality.

FIG. 3 illustrates an example of processing that the context handler 20can apply following the receipt (step 40) of a communication interruptrequest for an identified subscriber, for example generated by therating system 17.

The handler 20 looks up the context that it stores for the subscriberconcerned (step 41) to determine whether the latter has an atomicsection in progress (SA(j)=TRUE for a session j of the subscriber). Ifhe has, it compares the current time with the atomic section start timenoted in the record j, to determine whether the atomic section beganless than a predefined duration T₀ ago, for example around one minute(step 42). If this duration T₀ is not exceeded, the process returns totest 41, which means that the interrupt request is not served unless theindicator SA(j) returns to the value FALSE. The interruption of thecommunication is validated by the context handler 20 (step 43) only whentest 41 reveals no atomic section in progress, or when the test 42 showsthat the timer T₀ has expired. The context handler 20 then orders thesupervision platform 10 to notify the customer of the impendinginterruption, followed by the core network 2, so that the latter canterminate the communication.

The interruption validation performed in the step 43 does notnecessarily concern all the current sessions for the subscriberconcerned, particularly in cases of differentiated service rating.

The interrupt request received in step 40 can in particular beselective, that is, concern only some of the sessions in progress forthe subscriber, the screening of steps 41 and 42 being limited to thesesessions. Such a case can occur if the rating system 17 incorporates aservice cone processing logic and formulates its interrupt requestsaccordingly.

In another embodiment, the service cone processing logic is at leastpartly present in the context handler 20 which, when it receives aninterrupt request for a given service, takes account of this logic whenlooking up the atomic section indicators and the decisions to interruptthe services.

The timer T₀ is optional. It protects the operator against abusive useof the atomic sections by the customer. To the same end, a mechanism canalso be provided to prevent the customer from beginning a new atomicsection in a circumstance where a communication interruption invoked byan IS component of the CC&B would not be carried out immediately becauseof an atomic section already in progress. The supervision platform 10 isthen ordered to respond to the detection for this subscriber of anatomic section start type event by notifying him that his action cannotbe pursued.

The duration T₀ can be chosen at the level of the context handler 20. Itcan also depend on the service or the type of atomic section concerned,and be chosen by the service designer and specified to the supervisionplatform 10 by the agent made available to the service designer. Anumber of methods can then be envisaged for implementing the timer. Oneof these consists in the platform 10 flagging an end of atomic sectionto the handler 20 when the timer, counted down by this platform 10 fromthe start of this atomic section, has timed out. Another possibility isfor the platform 10 to indicate the duration T₀ to be taken intoconsideration to the handler 20 at the same time as it flags the startof the atomic section.

1. An on-line service provision method, wherein a service sessionsupervision platform (10) is placed between an access network (1) and aninput node (12) of a service-hosting network, the method comprising thefollowing steps in relation to at least one service: a priori defining,in the running of said service, at least one atomic section consistingof a determined sequence of events involved in message exchanges with asubscriber, and identifying a first event at the start of the atomicsection and at least one second event at the end of the atomic section;and configuring the supervision platform so that it detects the eventsidentified in a session of said service in progress for a subscriber viathe access network and flags a start of atomic section for saidsubscriber in response to the detection of the first event and an end ofatomic section for said subscriber in response to the detection of asecond event, wherein a communication interrupt request from asubscriber is processed by ascertaining whether an atomic section is inprogress for said subscriber according to the atomic section beginningsand ends flagged by the supervision platform, in order to determinewhether the communication must at least partly be interruptedimmediately.
 2. The method as claimed in claim 1, wherein, in responseto a communication interrupt request for a subscriber, the immediateinterruption of the communication is prevented when said subscriber hasan ongoing atomic section for at least one service.
 3. The method asclaimed in claim 1, wherein, in response to a communication interruptrequest for a subscriber, the immediate interruption of thecommunication is prevented when said subscriber has an ongoing atomicsection for at least one service started less than a predetermined time(T₀) ago.
 4. The method as claimed in claim 3, wherein saidpredetermined duration (T₀) is specified to the supervision platform(10) for each atomic section.
 5. The method as claimed in any one of thepreceding claims, wherein a context handler (20) is provided tocommunicate with different functional units including the supervisionplatform (10), to store information on service sessions in progress forsubscribers via the access network (1), said information comprising anatomic section indicator kept up-to-date for each subscriber based onatomic section beginnings and ends flagged by the supervision platform.6. The method as claimed in any one of the preceding claims, wherein theaccess network comprises a cellular radio communication network (1). 7.The method as claimed in any one of the preceding claims, wherein theinput node of the service-hosting network comprises an Internet portal(12).
 8. An on-line service control system, comprising a service sessionsupervision platform (10) placed between an access network (1) and aninput node (12) of a service-hosting network, and a context handler (20)to communicate with different functional units including the supervisionplatform in order to store information on service sessions in progressfor subscribers via the access network, wherein at least one atomicsection consisting of a determined sequence of events which are involvedin message exchanges with a subscriber is a priori defined in therunning of at least one service by identifying a first event at thestart of the atomic section and at least one second event at the end ofthe atomic section, the supervision platform (10) including means fordetecting the events identified in a session of said service in progressfor a subscriber via the access network and for flagging to the contexthandler (20) a start of atomic section for said subscriber in responseto the detection of the first event and an end of atomic section forsaid subscriber in response to the detection of a second event, thecontext handler including means of keeping an atomic section indicatorstored for each subscriber up-to-date on the basis of atomic sectionbeginnings and ends flagged by the supervision platform and ofprocessing a communication interrupt request from a subscriber accordingto the atomic section indicator stored for said subscriber in order todetermine whether the communication must at least partly be interruptedimmediately.
 9. A service session supervision platform for an on-lineservice control system, comprising: means of connection on the one handto an access network (1) and on the other hand to an input node (12) ofa service-hosting network; means for communicating with an applicationserver managing at least one on-line service so as to receive from saidapplication server specification elements of at least one atomic sectionconsisting of a determined sequence of events involved in messageexchanges with a subscriber in the running of at least one service, saidspecification elements describing a first event at the start of theatomic section and at least one second event at the end of the atomicsection; means of analyzing traffic passing between the access networkand the input node of the service-hosting network to detect said firstand second events in a session of said service in progress for asubscriber via the access network; and means of communication with acontext handler (20) storing information on service sessions in progressfor subscribers via the access network, including at least one atomicsection indicator, to flag to the context handler (20) a start of atomicsection for said subscriber in response to the detection of the firstevent and an end of atomic section for said subscriber in response tothe detection of a second event.
 10. The supervision platform as claimedin claim 9, wherein the specification elements of at least one atomicsection include a timer duration (T₀) associated with said atomicsection, such that the atomic section is considered to be finished whenthe timer duration has elapsed since the start of the atomic section.11. A context handler for an on-line service control system, comprising:means of communication with different functional units including aservice session supervision platform (10) placed between an accessnetwork (1) and an input node (12) of a service-hosting network; meansof storing information on service sessions in progress for subscribersvia the access network, said information including, for at least oneservice session in progress for a subscriber, an atomic sectionindicator kept up-to-date on the basis of atomic section beginnings andends flagged by the supervision platform; and means of processing acommunication interrupt request from a subscriber according to theatomic section indicator stored for said subscriber in order todetermine whether the communication must at least partly be interruptedimmediately.
 12. The context handler as claimed in claim 11, wherein theinterrupt request processing means are arranged to determine selectivelywhich current sessions for the subscriber are to be interrupted.
 13. Thecontext handler as claimed in claim 12, wherein the selectivedetermination is performed on the basis of sessions specified in theinterrupt request, taking into account atomic section indicators storedfor the subscriber.
 14. The context handler as claimed in claim 12,wherein the selective determination is performed according to apredefined service hierarchy logic, taking into account atomic sectionindicators stored for the subscriber.
 15. A software agent for anon-line service developer, comprising instructions for performing thefollowing operations on running the software agent in a computer machinecommunicating with a service session supervision platform (10) placedbetween an access network (1) and an input node (12) of aservice-hosting network: determination, in the running of a service, ofat least one atomic section consisting of a determined sequence ofevents involved in message exchanges with a subscriber; identificationof a first event at the start of the atomic section and of at least onesecond event at the end of the atomic section; and configuration of thesupervision platform so that it detects the events identified in asession of said service in progress for a subscriber via the accessnetwork and flags a start of atomic section for said subscriber inresponse to the detection of the first event and an end of atomicsection for said subscriber in response to the detection of a secondevent.
 16. The software agent as claimed in claim 15, wherein thesupervision platform (10) configuration operation performed on runningthe software agent includes a configuration of the supervision platformso that it flags atomic section beginnings and ends to a context handler(20) storing information on service sessions in progress for subscribersvia the access network, including at least one atomic section indicator.17. The software agent as claimed in claim 15 or 16, wherein thesupervision platform (10) configuration operation performed on runningthe software agent includes the specification of a timer duration (T₀)associated with at least one atomic section, such that the atomicsection is considered to be ended when the timer duration has elapsedsince the start of the atomic section.